Experimental for the influence of THF on the hydrate separation effect of high concentration CH4 gas

In order to improve the hydrate separation effect of highly concentrated CH4 gas,authors studied the hydrate separation experiment on a high concentration CH4 gas (60% CH4 ,32% N2 and 8% O2 ) under the condition of dif-ferent concentrated THF solutions whose concentration were 2. 5% -5. 5% ,and three kinds of initial pressures(1． 5, 2. 5 and 3. 5 MPa). In combination with the analysis results of gas chromatography,the effect of THF concentration and initial pressure on the recovery and separation factor of CH4 were investigated,the hydration products of micro crystalline structure characteristics of the high concentration CH4 gas were analyzed by Raman spectroscopy,under the condition that the THF concentration was 5. 5% ,the initial temperature was 2 ℃ ,and the pressure was 1. 5 MPa. The results indicate that the CH4 recovepressure. When the concentration of THF is 2. 5% -4. 5% ,the CH4 recovery increases at first and then decreases with the increase of initial pressure. When the concentration of THF is 5. 5% ,the CH4 recovery increases with the increase of initial pressure,the separation factor decreases with the increase of initial pressure in the four concentration of THF sol1u2tion. THF is involved in the hydration reaction and occupies the large cages (51264 ),then provides the small cages (5 ) skeleton for gas,CH4 has precedence to N2 and O2 ,THF—CH4—H2 O forms the hydrate of structure II.ry and separation factor increase with the increase of THF concentration at the same